Potential energy stored by planets and grand minima events

Recently, Wolff & Patrone (2010), have developed a simple but very interesting model by which the movement of the Sun around the barycentre of the Solar system could create potential energy that could be released by flows pre-existing inside the Sun. The authors claim that it is the first mechanism showing how planetary movements can modify internal structure in the Sun that can be related to solar cycle. In this work we point out limitations of mentioned mechanism (which is based on interchange arguments), which could be inapplicable to a real star. Then, we calculate the temporal evolution of potential energy stored in zones of Sun's interior in which the potential energy could be most efficiently stored taking into account detailed barycentric Sun dynamics. We show strong variations of potential energy related to Maunder Minimum, Dalton Minimum and the maximum of Cycle 22, around 1990. We discuss briefly possible implications of this putative mechanism to solar cycle specially Grand Minima events.Facultad de Ciencias Astronómicas y Geofísica

Orbital migrations in planetesimal discs: N-body simulations and the resonant dynamical friction

We have performed N-body numerical simulations of the exchange of angular momentum between a massive planet and a 3D Keplerian disc of planetesimals. Our interest is directed at the study of the classical analytical expressions of the lineal theory of density waves, as representative of the dynamical friction in discs 'dominated by the planet' and the orbital migration of the planets with regard to this effect. By means of a numerical integration of the equations of motion, we have carried out a set of numerical experiments with a large number of particles (N ≥ 10 000), and planets with the mass of Jupiter, Saturn and one core mass of the giant planets in the Solar system (Mc = 10M⊕). The torque, measured in a phase in which a 'steady forcing' is clearly measurable, yields inward migration in a minimum-mass solar disc (∑ ∼ 10 g cm-2 ), with a characteristic drift time of ∼ a few 106 yr. The planets predate the disc, but the orbital decay rate is not sufficient to allow accretion in a time-scale relevant to the formation of giant planets. We found reductions of the measured torque on the planet, with respect to the linear theory, by a factor of 0.38 for Mc, 0.04 for Saturn and 0.01 for Jupiter, due to the increase in the perturbation on the disc. The behaviour of planets whose mass is larger than Mc is similar to the one of type II migrators in gaseous discs. Our results suggest that, in a minimum mass, solar planetesimals disc, type I migrations occur for masses smaller than Mc, whereas for this mass value it could be a transition zone between the two types of migration.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Orbital migrations in planetesimal discs: N-body simulations and the resonant dynamical friction

We have performed N-body numerical simulations of the exchange of angular momentum between a massive planet and a 3D Keplerian disc of planetesimals. Our interest is directed at the study of the classical analytical expressions of the lineal theory of density waves, as representative of the dynamical friction in discs 'dominated by the planet' and the orbital migration of the planets with regard to this effect. By means of a numerical integration of the equations of motion, we have carried out a set of numerical experiments with a large number of particles (N ≥ 10 000), and planets with the mass of Jupiter, Saturn and one core mass of the giant planets in the Solar system (Mc = 10M⊕). The torque, measured in a phase in which a 'steady forcing' is clearly measurable, yields inward migration in a minimum-mass solar disc (∑ ∼ 10 g cm-2 ), with a characteristic drift time of ∼ a few 106 yr. The planets predate the disc, but the orbital decay rate is not sufficient to allow accretion in a time-scale relevant to the formation of giant planets. We found reductions of the measured torque on the planet, with respect to the linear theory, by a factor of 0.38 for Mc, 0.04 for Saturn and 0.01 for Jupiter, due to the increase in the perturbation on the disc. The behaviour of planets whose mass is larger than Mc is similar to the one of type II migrators in gaseous discs. Our results suggest that, in a minimum mass, solar planetesimals disc, type I migrations occur for masses smaller than Mc, whereas for this mass value it could be a transition zone between the two types of migration.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Potential energy stored by planets and grand minima events

Recently, Wolff & Patrone (2010), have developed a simple but very interesting model by which the movement of the Sun around the barycentre of the Solar system could create potential energy that could be released by flows pre-existing inside the Sun. The authors claim that it is the first mechanism showing how planetary movements can modify internal structure in the Sun that can be related to solar cycle. In this work we point out limitations of mentioned mechanism (which is based on interchange arguments), which could be inapplicable to a real star. Then, we calculate the temporal evolution of potential energy stored in zones of Sun's interior in which the potential energy could be most efficiently stored taking into account detailed barycentric Sun dynamics. We show strong variations of potential energy related to Maunder Minimum, Dalton Minimum and the maximum of Cycle 22, around 1990. We discuss briefly possible implications of this putative mechanism to solar cycle specially Grand Minima events.Facultad de Ciencias Astronómicas y Geofísica

Dynamical characterization of the last prolonged solar minima

The planetary hypothesis of the solar cycle is an old idea in which the gravitational influence of the planets has a non-negligible effect on the causes of the solar magnetic cycle. In this work we looked for a possible causal link in relation with solar barycentric dynamics and prolonged minima events. We searched for particular changes in the Sun's acceleration and concentrated on long-term variations of the solar cycle. We show how the orbital angular momentum of the Sun evolves and how the inclination of the solar barycentric orbit varies during the epochs of orbital retrogressions. In particular, at these moments, the radial component of the Sun's acceleration (i.e., in the barycentre-Sun direction) had an exceptional magnitude. These radial impulses occurred at the very beginning of the Maunder Minimum, during the Dalton Minimum and also at the maximum of cycle 22 before the present extended minimum. We also found a strong correlation between the planetary torque and the observed sunspots international number around that maximum. We apply our results in a novel theory of Sun-planets interaction that it is sensitive to Sun barycentric dynamics and found a very important effect on the Sun's capability of storing hypothetical reservoirs of potential energy that could be released by internal flows and might be related to the solar cycle. This process begins about 40 years before the solar angular momentum inversions, i.e., before Maunder Minimum, Dalton Minimum, and before the present extended minimum. Our conclusions suggest a dynamical characterization of peculiar prolonged solar minima. We discuss the possible implications of these results for the solar cycle including the present extended minimum. (Please read the complete Abstract in the paper)Comment: 17 pages, 6 figures, ACCEPTED in Advances in Space Researc

A Comparison of the SAO-Hipparcos reference frames

The reference systems defined by the SAO and Hipparcos catalogues are compared using vector spherical harmonic analysis. The differences between astrometric data in both catalogues have been grouped into different data sets and separate harmonic analysis performed on them. The Fourier coefficients yield estimates of systematic errors in SAO catalogue.Fil: Arias, E. F.. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Cionco, Rodolfo Gustavo. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; ArgentinaFil: Orellana, Rosa Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Vucetich, Hector. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Orbital migrations in planetesimal discs: N-body simulations and the resonant dynamical friction

We have performed N-body numerical simulations of the exchange of angular momentum between a massive planet and a 3D Keplerian disc of planetesimals. Our interest is directed at the study of the classical analytical expressions of the lineal theory of density waves, as representative of the dynamical friction in discs 'dominated by the planet' and the orbital migration of the planets with regard to this effect. By means of a numerical integration of the equations of motion, we have carried out a set of numerical experiments with a large number of particles (N ≥ 10 000), and planets with the mass of Jupiter, Saturn and one core mass of the giant planets in the Solar system (Mc = 10M⊕). The torque, measured in a phase in which a 'steady forcing' is clearly measurable, yields inward migration in a minimum-mass solar disc (∑ ∼ 10 g cm-2 ), with a characteristic drift time of ∼ a few 106 yr. The planets predate the disc, but the orbital decay rate is not sufficient to allow accretion in a time-scale relevant to the formation of giant planets. We found reductions of the measured torque on the planet, with respect to the linear theory, by a factor of 0.38 for Mc, 0.04 for Saturn and 0.01 for Jupiter, due to the increase in the perturbation on the disc. The behaviour of planets whose mass is larger than Mc is similar to the one of type II migrators in gaseous discs. Our results suggest that, in a minimum mass, solar planetesimals disc, type I migrations occur for masses smaller than Mc, whereas for this mass value it could be a transition zone between the two types of migration.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Differences in the Same OMI/MLS Aura Tropospheric Ozone Data Set Published Before and After January 2013

On the website "NASA Goddard Homepage for Tropospheric Ozone", global data of tropospheric ozone obtained from observations of OMI and MLS Aura satellite instruments, are reported. In mid-2013, the data was covering the period between October 2004 and January 2013. Subsequently, in early 2014, the time series was extended until December 2013. At present time, the published series has been extended to December 2014. Analysing this new series, we observed that the data already published to January 2013 had been replaced; not only the missing months of 2013 were added but all the values published since 2004 were recalculated. We present the detected differences in the comparison between common data to both time series (the original, before January 2013, and the new one, currently published on the website). These differences are important considering that they represent the result of the same satellite observation and should be considered when comparing results before/after January 2013, especially when adopting a certain confidence level in the spectral analysis of these data to intraseasonal scale. A warn of caution is suggested in the use of these observations and intercomparison with other values of these and other instruments, because of possible recurrent problems of instrumental calibration.Fil: Cionco, Rodolfo Gustavo. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Agosta Scarel, Eduardo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Rodriguez, Rubén L.. Universidad Tecnológica Nacional; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Quaranta, Nancy Esther. Universidad Nacional de La Plata; Argentina. Universidad Tecnológica Nacional; Argentin